An Integrated Starter Generator (ISG) system is generally used for the purpose of starting an Internal Combustion (IC) engine and for electric power generation. Typically an ISG system has a single electric machine connected to a crankshaft of a vehicle. For starting of IC engine, the electric machine is rotated which, in turn rotates the crankshaft. Such rotation should be at a sufficiently high speed before the self-sustaining combustion process can commence inside the IC engine. During a power generation operation, crankshaft rotates the electric machine to generate electric power required to charge a battery and power other electrical loads of the vehicle.
In a conventional ISG system, an electronic control unit (ECU) is placed between a battery and an electric machine of a vehicle where the ECU regulates bidirectional flow of electric power between the battery and electric machine. During engine start operation, the ECU draws power from the battery and feeds it to drive the electric machine, whereas during power generation operation, it regulates flow of electric power from the electric machine to charge the battery and also supply power to other electrical loads.
Most ISG systems use a permanent magnet brushless electric machine (BLDC machine). Such machines consist of a stator made of a polyphase winding, and a rotor made of permanent magnets. For optimal operation of ISG system, the ECU needs to excite the stator windings in a particular sequence with respect to the position of the rotor of the electric machine. In this regard, multiple hall-effect based sensors are typically used for sensing rotor position. Such sensors are placed either inside the stator windings or a separate magnetic ring is used to trigger the hall-effect based sensors. In either case, the sensors are needed to be placed inside a casing of the IC engine. An alternative to hall-effect based sensors is to use an absolute angle sensor of the crankshaft. However, such sensor also needs to be placed inside the engine casing.
Since such sensors are placed inside engine casing, they are subjected to harsh operating conditions such as high temperature and vibrations, which make them prone to failure. Further, a special arrangement is required for mounting the sensors which adds cost and occupies space inside the engine casing. Furthermore, the sensors need to be connected to ECU using wires for providing signals from the sensors to the ECU. For this purpose, a provision for routing of wires from sensors to ECU is also required. Further, any damage to wires impairs operation of the ISG system.
In view of the above there exists a need in the art to at least address the above mentioned problems.